Recirculating delay line phase control system for use in producing a variable direction beam from a fixed transmitting array



June 6. 1967 RECIRCULATING DELAY LINE PHASE CONTROL SYSTEM FOR USE INPRODUCING A VARIABLE onmcnou BEAM FROM A FIXED Original Filed Nov. 25,1964 B. BRIGHTMAN TRANSMITTING ARRAY 5 Sheets-Sheet 1 ,rro-u T.D.M. nod"'OUTPUT LEvEL I :TRANSMISSION' wo-m MEANS i ,wO-mn I I64 OUTPUT RESER lLEVEL 1139 ['28 I344 364 sT R o E REVERSIBLE A I 6-11 VERTICAL I TIMEfiles PHASE 5 1" SLOT SL01- 5 COUNTER GENERATOR cOuNTER T i I l46-1n IAUDIO I PULSE l30 I l o6 1 A CARE MEANS I RESET: l34-m l36-m I RESET J M"9" L TIME T|ME SLOT SLOT I I04 /ll0 GENERATOR COUNTER l46-mn VERTICALPHASE PuL Es HORIZONTAL PHASE Hs n4 AND VERTICAL PHASE PuLsE GENERATORSHORIZONTAL REVERSIBLE us-1 SE HORIZONTAL PULSES PHASE v |l6--n couNTERf'OZ zz CLOCK PULSE FIG. FIG. GENERATOR fi 1A 1B June 6, BR GHT r3,324,453

RECIRCULATING DELAY LINE PHASE CONTROL SYSTEM FOR USE IN PRODUCING AVARIABLE DIRECTION BEAM FROM A FIXED TRANSMITTING ARRAY Original FiledNov. 23, 1964 3 Sheets-Sheet E IOU-11 lOO-ln I6011 g5 l?O-1n TRANSDUCERTRANSDUCER POWER AMP. POWER LINE cIRcuIT 7 LINE CIRCUIT i Aez-m 1 Isa-uI l56-1n 1 sToRE 1 I STORE OUTPUT ---1- --OUTPUT I GATE I GATE I E J I Ii I I l58-1 I l58-1n: I

I I o -m1 I |lOO-mn I [l6Om1 l I KISO-mn I TRANSDUCER I TRANSDUCER IPOWER AMP. POWER AMP. 1 LINE CIRCUIT LINE CIRCUIT 5 -I62-m1 1 I62-mnISS-mn l56-mn STORE sToRE l46-m-1 OUTPUT OUTPUT GATE 1- GATE I l46-mn C551 sToRE STORE /l54-1 flsq-n rl48-1 I48n sToRE sToRE INPUT INPUT GATEGATE Iso-i wlSO-n L r1204. rlZO-fl DELAY LINE DELAY LINE AUD|O FREQAUDIO FREQ- GENERATOR GENERATOR lzz June 6, 1967 BRIGHTMAN 3,324,453

RECIRCULATING DELAY LINE PHASE CONTROL SYSTEM FOR USE IN PRODUCING AVARIABLE DIRECTION BEAM FROM A FIXED TRANSMITTING ARRAY Original FiledNov. 23, 1964 5 Sheets-Sheet 3 CLOCK VPULSE 208 200 201 202 20s PHASE WMONOSTABLE CONDROL DELAY MULTIVIBRATOR OUTPUT 1 2f J mss w 124 y a L 1210 am RESET i I AUDIOICONTROL M TO CONTROL MEANS AUDIO FREQ. GENERATORVIRTUAL PLANAR ARRAY FROM CONTROL MEANS [HZ-A 3OO-l '8 ue-m ll6-IB ug-lcHORIZONTAL DELAY ORDER TO DELAY LINE l I PHASE 30o-" REVERSING i AUDIOFREQ.

- 1 l I GENERATOR AY LINE I C|RCU|T 17 20 llG-nB Il6-nC ll6-nA UnitedStates Patent Barrie Brightmc n, Webster, N.Y., assignor to GeneralDynamics Corporation, Rochester, N.Y., a corporation of DelawareContinuation of application Ser. No. 413,010, Nov. 23,

1964. This application Oct. 18, 1966, Ser. No. 587,625 13 Claims. (Cl.340-5) This is a continuation of application Ser. No. 413,010 filed Nov.23, 1964, and now abandoned.

This invention relates to a phase control system and, more particularly,to such a system for producing a variable direction beam from a fixedtransmitting array.

It is well known that a fixed transmitting array, such as an arraycomposed of a plurality of stationary sonar transducers, may be utilizedto transmit a directional beam of energy at any transmitting frequency,the direction of the beam being a function of the relative phasedifference of the respective signals of the transmitting frequencyapplied to the respective transducing elements making up the array.

For instance, it signals having the same frequency and phase are appliedto each transducer of a planar array of equally spaced transducersarranged in rows and I columns, the array will transmit a broadside beamin a direction perpendicular to the planar array. On the other hand, ifthe phase of the signal applied to the respective transducers of eachcolumn is delayed by a time interval with respect to the phase of thesignal applied to the respective transducers of the column immediatelyto its left which time interval is equal to the distance betweenadjacent transducers in each row divided by the velocity of propagationof the transmitted energy in the medium surrounding the transducers, anend-fire beam substantially parallel to the planar array will bepropagated to the right. Similarly, if this time delay is more thanzero, but is less than that necessary to produce an end-fire beam, abeam of energy will be propagated at some azimuth angle in the firstquadrant which angle is a function of this time delay. In like manner,if the phase of the signal applied to the transducers of each column isdelayed by an appropriate time interval with respect to the phase of thesignal applied to the transducers of the column immediately to itsright, a beam of energy will be propagated at some azimuth angle in thesecond quadrant. Just as the azimuth angle may be controlled bycontrolling the relative time delay between adjacent columns'of a planararray, the elevation angle may be controlled by controlling the relativetime delay between adjacent rows of a planar array.

The reason that a directional beam is produced is that wave energytransmitted by each of the transducers will algebraically add up tore-enforce each other in only a certain direction which depends solelyon the positions of the transducers in the array and the relative phasedifference existing between signals applied to adjacent transducers. Inall other directions, the wave energy transmitted from each of therespective transducers of the array will algebraically add up to canceleach other.

Although in the above discussion it has been assumed that the fixedarray is a planar array, this is not necessarily the case. It ispossible by properly choosing the positions of the transducers in anon-linear, non-planar array, in a manner to be described 'in detailbelow, and by inserting pre-selected fixed phase delays in the signalsapplied to the transducers thereof to produce a virtual planar arraywhich is displaced and/or rotated with respect to the actual array. Sucha virtual plannar array at a predetermined angle with respect to anactual planar array may also be produced by inserting preselected fixedphase delays in the signals applied to the transducers thereof.

Since in most cases it is desirable to produce a directional beam ofrelatively narrow width, and a beam becomes narrower as the number oftransducers in the transmitting array increases, it is often necessaryto provide an array consisting of several hundred columns and rows oftransducers in order to produce a beam of sufficient directivity. Thisrequires that the minimum phase difference in the signals applied to thetransducers of the various columns and rows be quite small, in the orderof one degree or less. 7

It will be appreciated that with ordinary space division techniques itis quite difiicult and expensive to provide each one of hundreds oftransducers with a sinusoidal signal of a transmitting frequency whichis accurately phased to a fraction of one degree for each selected oneof a relatively large plurality of different available beam directions.This problem has limited the use of fixed transmitting arrays forproducing a variable direction beam.

The present invention contemplates the utilization of time divisionmultiplex techniques and, more particularly, the use, of recirculatingdelay lines to produce the multilicity'v of needed sinusoidal signals ofdifferent phases. Time division techniques may also be used todistribute the sinusoidal signals to the appropriate transducers forforming a beam in any one of a large plurality of different directions.Furthermore, for proper beam forming the relative levels of sinusoidalsignals applied to the various transducers must be controlled. Timedivision multiplex techniques are also utilized for such level control.

It is therefore an object of the present invention to provide animproved phase control system for producing a variable direction beamfrom a fixed transmitting array.

It is a further object 'of the present invention to provide such a phasecontrol system utilizing time division multiplex techniques.

It is a still further object of the present invention to provide such atime division multiplex phase control system incorporating recirculatingdelay lines.

These and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription, taken together with the accompanying drawings, in which:

FIGS. 1A and 18, when placed next to each other as shown in FIG. 1C,illustrate a block diagram of a preferred embodiment of the presentinvention;

FIG. 2 is a block diagram showing the details of each delay line audiofrequency generator utilized in the embodiment shown in FIGS. 1A and 1B;

FIG. 3 illustrates the relationships of a non-planar array with avirtual planar array produced therefrom; and

FIG. 4 illustrates a modification in the embodiments shown in FIGS. 1Aand 1B utilized in producing a virtual planar array.

Referring to FIGS. 1A and 13, there is diagrammatically shown a planararray of sonar transducers arranged in m rows and n columns, namely,transducers -11 100-112; 100-ml 100-mn. The spacing between adjacentcolumns of transducers is equal and the spacing between adjacent rows oftransducers is equal, but the column spacing and the row spacing are notnecessarily equal to each other.

The phase control system for producing a variable direction beam fromthis planar array of transducers is synchronized by clock pulses havinga very high frequency, such as 15 mc., for instance, from clock pulsegenerator 102. Horizontal phase and vertical phase generators 104 towhich clock pulses are applied may consist of a plurality of clock pulsefrequency dividers or a plurality of clock pulse synchronizedmultivibrators. In any event, control means 106, which either manuallyand/or automatically supplies all control information, provideshorizontal phase and vertical phase generators 104 with beam directioninformation as to the desired value of horizontal phase delay frequencyand vertical phase delay frequency. This information is utilized toeither control the tuning of the individual clock pulse synchronizedmultivibrators or the divisor of the individual frequency dividers, asthe case may be, in block 104. In this manner variable frequencyhorizontal phase pulses are produced on conductor 108 which have a pulserepetition period which is an exact integral multiple of the clock pulserepetition period, and variable frequency vertical phase pulses areproduced on conductor 110 which have a pulse repetition period which isan exact integral multiple of the clock pulse repetition period.

The horizontal phase pulses on conductor 108 are applied as an input toreversible horizontal phase counter 112. When a beam direction in thefirst quadrant is selected by control means 106, control means 106applies a control signal to reversible horizontal phase counter 112 overconductor 114 which results in reversible horizontal phase counter 112counting in a forward direction the horizontal phase pulses appliedthereto over conductor 108. When a beam direction in the second quadrantis selected by control means 106, cont-r01 means 106 applies a controlsignal to reversible horizontal phase counter 112 over conductor 114which results in reversible horizontal phase counter 112 counting in areverse direction the horizontal phase pulses applied thereto over con-Iductor 108.

When reversible horizontal phase counter 112 is counting in a forwarddirection, an output pulse will be produced thereby in sequence on eachindividual one of conductors 116-l 116-n in that order in response toeach successive horizontal phase pulse applied thereto over conductor108. When reversible horizontal phase counter 112 is counting in areverse direction, an output pulse will 'be produced thereby in sequenceon each individual one of conductors 116-n 116-l in that order inresponse to each successive horizontal phase pulse applied thereto overconductor 108. Since the pulse repetition period of the horizontal phasepulses is variable, the time delay between the application of a pulse tosuccessive ones of conductors 116-l 116-n in a forward or reversedirection, as the case may be, is varied accordingly. In addition,control means 106, for a reason to be described below, applies a resetsignal to counter 112 at certain times over conductor 118 which iseffective in resetting counter 112.

The respective pulses on each individual-one of conductors 116-l 116-nare applied, as shown, as a first input to the corresponding one ofdelay line audio frequency generators 120-1 120-n. Clock pulses fromclock pulse generator 102 are applied in common as a second input to allof delay line audio frequency generators 120-l 120-n, a reset signalfrom control means 106 is applied in common as a third input overconductor 124 to all of delay line audio frequency generators 120-1120-n, and an audio control signal from control means 106 is applied incommon as a fourth input over conductor 126 to all of delay line audiofrequency generators 120-! 120-n.

The structure of any delay line audio frequency generators 120-1 120-n,all of which are identical to each other, is shown in FIG. 2. Referringnow to FIG. 2, the phase control pulse which arrives on the conductor116 individual to any delay line audio frequency generator as the firstinput thereto is applied through OR gate 200 as the input to-delay line201. The pulse emerges from delay line 201 after a given delay which isdetermined by the length of delay line 201. After being amplified byamplifier 202, the pulse emerging from the output of delay line 201 isapplied as an input to monostable multivibrator 204, which is setthereby. Monostable multivibrator 204, after being set, remains in itsset condition for a given time interval which is a function of themagnitude of a bias voltage applied thereto. The audio control signal onconductor 126, which is applied as the fourth input to the delaylineaudio frequency generator, provides a bias voltage, under the control ofcontrol means 106, which has a magnitude which is a function of thedesired audio frequency. At the end of this given time interval,monostable multivibrator 204 automatically resets, in a manner wellknown in the art of monostable multivibrators, and produces an outputpulse therefrom which is coincident in time with the resetting thereof.The output pulse from monostable multivibrator 204 is applied as both aset and reset input to flip-flop 206 and is also applied as a firstinput to AND gate 208. AND gate 208 also receives as a second inputthereto the clock pulses on conductor 122 which are applied as a secondinput to the delay line audio frequency generator, and also receives asa third input to AND gate 208 at the reset signal on conductor 124,which is applied as a third input to the delay line audio frequencygeneratorfrom control means 106. The signal on conductor 124 is such asto normally enable AND gate 208, AND gate 208 only being disabled atthose certain times when a reset signal is applied to conductor 124under the control of control means 106.

Therefore, AND gate 208 normally produces as an output a reclocked pulsein response to an output pulse from monostable multivibrator 204. Thisreclocked pulse is applied as a recirculation input to delay line 201through OR gate 200. Thus it will be seen that AND gate 208 forms partof the recirculation loop for the delay means which consist of delayline 201 in series with the variable delay produced by monostablemultivibrator 204.

Thus, due to this recirculation, a series of time-spaced pulses having apulse repetition period equal to the total delay provided by the sum ofthe individual delays due to delay line 201, monostable multivibrator204 and any slight delay provided 'by amplifier 202 and therecirculation loop will be produced at the output of monostablemultivibrator 204. Of course, this total delay may be varied in'accordance with the audio control signal on conductor 126.

The odd occurring ones of these time-spaced pulses are effective insetting flip-flop 206, and the even occurring ones of these time-spacedpulses are effective in resetting flip-flop 206. Thus, flip-flop 206will produce as an output a square wave having twice the period of thetotal delay provided by the recirculation delay means. The fundamentalfrequency of the square wave can therefore be varied merely bycontrolling the bias applied to monostable multivibrator 204 by theaudio control signal on conductor 126. The control signal on conductor126 may have only an adjustable D.C. value, in which case an audiosquare wave having a fixed fundamental frequency determined by thisvalue will be produced by flip-flop 206. On the other hand, the controlsignal on conductor 126 may have an alternating frequency component withrespect to an adjustable D.C. value, in which case an audio square Wavehaving a fundamental frequency which is frequency-modulated may beproduced.

It will be seen that the relative phase of the audio square waveproduced by flip-flop 206 in response to the application of a phasecontrol pulse on conductor 116 applied to any particular delay lineaudio frequency generator depends solely on the relative instant of timeat which the phase control pulse on conductor 116 of that delay lineaudio frequency generator is applied. Further, the presence of a resetpulse on conductor 124 will disable AND gate 208 to thereby open therecirculation loop and erase the recirculating pulse and the audiosquare wave produced by flip-flop 208 which results therefrom;

phase of the fundamental frequency of the applied audio square wave. 1

Referring back to FIGS. 1A and IE, it will be seen that each of delayline audio frequency generators 120-1 120-n will produce a sinusoidalwave at its output. It will be further seen that the relative phasedelay between respective sinusoidal wave outputs produced from adjacentones of delay line audio frequency generators 120-1 120-11 will be equalto the pulse repetition period of the horizontal phase pulses onconductor 108, which depend upon the azimuth of the desired beamdirection. When, under the control of control means 106, it i desired tochange the desired beam direction, or to compensate, under the controlof control means 106, for yaw or pitch of the vessel on which the fixedtransmitting array is mounted, it is necessary to change this relativephase delay between adjacent ones of delay line audio frequencygenerators 120-1 120-21. To accomplish this, control means. 106 altersthe pulse repetition period of the horizontal phase pulses on conductor108, applies a reset signal to reversible horizontal phase counter 112over conductor 118, and applies a reset pulse over conductor 126 as athird input to each of delay line audio frequency generators 120-1120-11 to cause the cancellation of the then circulating delay linepulses. This will result in new phase control pulses being applied byreversible horizontal phase counter 112 over conductors 116-1 116-" tothe corresponding ones of delay line audio frequency generators 120-1120-n to set up sinusoidal wave outputs therefrom having the new desiredrelative phase delay between adjacent sinusoidal wave outputs, whichwill be maintained until this relative phase delay i again changed inthe same manner under the control of control means 106.

The vertical phase pulses on conductor 110, which have a pulserepetition period which, under the control of control means 106, dependson the elevation angle of the desired beam direction is applied as afirst input to reversible horizontal phase counter 128. When a beamdirection in the first quadrantis selected by control means 106, control means 106 applies a control signal to reversible vertical phasecounter 128 over conductor 130 which results in reversible verticalphase counter 128 counting in a forward direction the vertical phasepulses applied thereto over conductor 110. When a beam direction in thefourth quadrant is selected by control means 106, control means 106applies a control signal to reversible vertical phase counter 128 overconductor 130 which results in reversible vertical phase countercounting in a reverse direction the vetrical phase pulses appliedthereto over conductor 110.

When reversible vertical phase counter 128 is counting in a forwarddirection, an output pulse will be produced thereby in sequence on eachindividual one of conductors 132-1 132-m in that order in response toeach successive vertical phase pulse applied thereto over conductor 110.When reversible vertical phase counter 128 is counting a reversedirection, an output pulse will be produced thereby in sequence on eachindividual one of conductors 132-m 132-1 in that order in response toeach successive vertical phase pulse applied thereto over conductor 110.Since the pulse repetition period of the vertical phase pulses isvariable, the time delay between the application of a pulse tosuccessive ones of conductors 132- 132-m in a forward or reversedirection, as the case may be, is varied accordingly. In addition,control means 106,

for a reason to be described below, applies a reset signal to counter128 as well astime slot generators 134-1 134-m and time slot counters136-1 136-m at certain times over conductor 138 which is effective inre- 6 setting counter 128 as well as resetting time slot generators134-1 134-m and time slot counters 136-l Each of time slot generators134-1 134-m may include a multivibrator which is synchronized by clockpulses applied thereto over conductor 122 which when enabled producestime slot pulses at some fixed integral multiple of the clock pulseperiod, such as at a frequency of l mc. Each time slot generator furtherincludes a bistable element which when set enables the multivibratorthereof and which when reset disables the multivibrator thereof. Thereset signal applied to each of time slot generators 134-1 134-m iseffective in resetting the bi- 1 stable element thereof, while thevertical phase control pulses appearing on individual conductors 132-1132-m is effective in setting the bistable element thereof.

As shown, each of time slot generators 134-1 134-m applies time slotpulses generated thereby as a first input to the corresponding one oftime slot counters 136-1 136-m over the corresponding one of conductors140-1 140-m.

Audio pulse timer 142, under the control of control means 106, appliesan enabling signal in common as a second input to all of time slotcounters 136-1 136-m over conductor 144 only during intermittenttransmitting periods, each of which may be in the order of seconds. Eachtransmitting period, under the control of audio pulse timer 142, isfollowed by a receiving period, which also may be in the order ofseconds, during which a disabling signal is applied in common as thesecond input to all of time slot counters 136-1 136-m over conductor144. 7

Each of time slot counters 136-1 136-m includes a cyclic counter havinga count capacity of n and AND gate means which is enabled only inresponse to the presence of an enabling signal from audio pulse timer142 over conductor 144. The counter of each time slot countter 136-1136-m is advanced in response to each time slot pulse from thecorresponding one of time slot generators 134-1 134-m applied as a firstinput there to over thecorresponding one of the conductors 140-1 140-m.The AND gate means included in each of time slot counters 136-1 136-monly when enabled feeds the output of the counter thereto to theappropriate one of the output conductors thereof, e.g., 146-11 146-1n;;146m1 146-mn, in accordance with the count manifested by the counter.

It will be seen that the counter of each time slot counter 136-1 136-macts as a commutator or steering circuit for forwarding only during eachtransmitting period the time slot pulses applied thereto in sequence toeach of the output conductors thereof, e.g., 146-11 146-1n; 146-ml146-mn, to provide a repetitive time frame composed of n time slots.

The counters of all of time slot counters 136-1 136-m are simultaneouslyreset to a home position thereof in response to a reset signal onconductor 138. Since reversible vertical phase counter 128, whenoperating in a forward direction, initiates the operation of time slotgenerator 134-1 134-m in sequence with a time delay between adjacenttime slot generators equal to one vertical phase pulse repetitionperiod, it will be seen that although the time frame frequency of all oftime slot counters'136-1 136-m is the same there will be a is justvequal to one vertical phase pulse repetition period.

The outputs of delay line audio frequency generators -1 120-n areapplied as individual inputs to each corresponding one of normallyclosed store input gates ,each time frame produced by time slot counter136-1 over conductors 146-11 146-111. However, the time slot pulsesappearing at the output of anyother single one of time slot counters136-2 (not shown) 136-m, rather than time slot counter 136-1, could justas easily be utilized to control the opening of store input gates 148-1148-11. The only thing that is important is that each store input gate148-1 .148-11 be squentially opened periodically during a different timeslot of each successive time frame.

When any one of store input gates 148-1 148-11 is opened, a sample ofthe instantaneous amplitude of the sinusoidal wave appearing at theoutput of the corresponding one of delay line audio frequency generators120-1 120-11, applied over the corresponding one of conductors 150-1150-n, is forwarded to the corresponding one of stores 152-1 152-n overthe corresponding one of conductors 154-1 154-12. Each of stores 152-1152-n registers the magntiude of the sample applied thereto for anentire time frame period until the next sample is applied thereto. Eachof stores 152-1 152-11.may consist of a capacitance, which is charged bythe sample applied thereto, feeding the input of a cathode follower oremitter follower. Since, as is well'known in the art, a cathode followeror emitter follower has a very high input impedance, no appreciabledischarge of the capacitance will take place during the single timeframe period which exists between the application of successive samplesthereto. Therefore, during this entire time frame period, the relativelylow impedance output of the cathode follower or emitter follower will bemaintained at a magnitude which is proportional to the magnitude of thesample then being stored by the capacitance of that store.

The output of each of stores 152-1. 152-11 is:

applied in common as an input to all the store output gatescorresponding with the column with which it is associated; i.e., theoutput of store 152-1 is applied in common as an input to normallyclosed store output gates 156-11 156-m1 over conductor 158-1; and theoutput of store 152-11 is applied in common as an input to normallyclosed store output gates 156-ln 156-mn over conductor 158-11.

The outputs from each of time slot counters 135-1 136-m is effective inopening the store output gates corresponding with the row with which itis associated; i.e., the time slot pulses appearing on conductors 146-11146-111 from time slot counter 136-1 during each successive time framesequentially open store out put gates 156-11 156-111 during differenttime slots thereof; and the time slot pulses appearing on conductors146-1111 146-nm from time slot counter 136-111 during each successivetime frame sequentially open store output gates 156-m1 156-m11 duringdifferent time slots thereof.

As shown in FIGS. 1A and 1B, the output of each store output gate isapplied as an input to the corresponding oneof transducer, poweramplifier, line circuits; i.e., the

Each transducer, power amplifier, line circuit includes a low-passfilter for reconstructing the sample into a sinusoidal wave having aphase which depends both on erators 120-1 it is associated and thevertical time delay experienced by that time slot counter correspondingto the row with which it is associated. This reconstructed sinusoidalwave is amplified by the poweramplifier included in each transducer,power amplifier, line circuit and then is converted from electricalenergy into sonic energy by the transducer included in each transducer,power amplifier, line circuit to cause the associated transducer totransmit a sonic wave having the same frequency and phase.

It will be seen that although in the embodiment shown in FIGS. 1A and 1Bthe delay line audio frequency gen- 120-11 correspond with each columnof transducers and the time slot counters 136-1 136-111 correspond witheach row .of transducers, it is possible to modify the embodiment shownin FIGS. 1A and lB to provide a delay line audio frequency generatorcorresponding with each row of transducers and a time slot generatorcorresponding with each column of transducers. Of course, in this case,the output of reversible horizontal phase counter 112 would feed thetime slot generators associated with each column and reversible verticalphase counter 128 would geed the audio delay line generators associatedwith each row.

In the manner that has beenv described up to now, signals having thedesired audio frequency in proper relative phase in accordance withdesired beam direction are applied to each of the transducer, poweramplifier, line circuits.

However, it is also necessary to control the relative amplitude of eachaudio signal to be transmitted by each transducer in accordance with theselected beam direction. This may be accomplished in the same mannerasdescribed in detail in the copending application (D-3004) entitled,Delay Counter Phase Control System for use in Producing a VariableDirection Beam from a Fixed Transmitting Array, by Uwe A. Pommerening,Ser. No. 412,956, filed Nov. 23, 1964, now abandoned, and assigned tothe same assignee as the present invention. Briefly, this isaccomplished, as shown in FIGS. 1A and 1B, by providing output levelstore 164, which may be a pre-programrned multichannel magnetic drum orcore store, for instance, which obtains information as to the the phaseof the sinuo'sidal wave emanating-from that 1 one of the delay lineaudio frequency generators -1 120-11 associated with the columnwithwhich desired beam direction from control means 106 over conductor 166which is synchronized by time slot pulses which may be obtained from anyone of the time slot generators, such as time slot generator 134-1, forinstance, and by providing conventional time division multiplex outputlevel transmission means 168 (the details of which are shown in saidcopending application), Which includes,

means for generating arepetitive time frame each including 11 timeslots, from time slot pulses applied thereto from time slot generator134-1. Output level store 164' in accordance with its program and thebeam direction information received thereby provides, during each timeslot of each time frame, a control pulse for opening some one of knormally closed level gates included in block 168, and more fullydescribed in said copending application, associated with each row oftransducers. Each level gate associated with any one row, when opened,applies a distinct one of k different voltage levels, V1 Vk, to a commontransmission highway (included within block 168 and more fully describedin said copending application) corresponding to that row.

'During each time frame the successive time slot pulses are effective insequentially opening line gates individually associated with thetransducer, power amplifier, line I circuits of each row (which areincluded in block 168 and are more fully described in said copendingapplication), so as to apply the selected ones of voltages V1 Vk foreach row as an input to the appropriate one of the transducer,poweramplifier, line circuits of that row in accordance withconventional time division multiplex techniques, i.e., over conductors170-11 170-1n associated with the top row; and over conductors 170-m1170-mn associated with the bottom row.

shape, such as elliptical, for instance.

As more fully described in said copending application, each of thetransducer, power amplifier, line circuits includes a rectifier forproviding a DC. voltage which has a magnitude proportional to that oneof voltage Vl Vk then being applied thereto. This D.C. voltage derivedin each transducer, power amplifier, line circuit is utilized to controlthe gain of the power amplifier thereof, so that the amplitude of thesinusoidal wave being transmitted is controlled thereby.

The basic preferred embodiment shown in FIGS. 1A and 1B is for use witha physically planar array. At times the actual physical array is notplanar but has some other As shown in FIG. 3, a vertual planar array,wherein the effective distance "11 between adjacent transducers on thevirtual planar array is equal, may be derived from an actual non-planararray by locating the physical transducers of the nonplanar array atunequal distances a a from each other and providing an appropriate fixeddelay for each transducer. More particularly, as shown in FIG. 3, thedistances a a a line in accordance with the desired location of thevirtual planar array, laying out equidistant points on this line, thedistancebetween adjacent points being b, drawing straight lines betweenthese points and the origin of the non-planar array, and locating thetransducers at the intersection of these straight lines and thenon-planar array. The distance between the position of a transducer onthe non-planar array and the point corresponding thereto on the virtualplanar array manifests a fixed time delay which is equal to thisdistance divided by time velocity of sound in the surrounding medium.

The embodiment shown in FIGS. 1A and 1B may be easily modified, as shownin FIG. 4, to provide this needed fixed delay for each transducer bysubstituting a nonreversible horizontal phase counter 1-12A for counter112 shown in the embodiment of FIGS. 1A and 1B. 'F-urther, in FIG. 4,the output of the horizontal phase counter, rather than being applieddirectly to delay line audio frequency generators 120-l 120-n overcorresponding conductors 116-l 116-11, is applied, as shown, asrespective inputs to individual fixed delay lines 300l 300-n, each ofwhich provides the needed fixed delay for each transducer, overcorresponding conductors 116-lA 116-nA. The output of the individualdelay lines 300l 300-12 are applied as inputs to order reversing circuit302 over corresponding conductors 116-18 1I6nB, and the individualoutputs of order reversing circuit 302 are applied to thecorrespondingones of delay line audio frequency generators 120l 120n over thecorresponding ones of conductors 116-1C 116nC. In addition, orderreversing circuit 302 receives information from control means 106 as towhether the desired beam direction is in the first or second quadrantover conductor 114A. When a beam direction in the first quadrant isselected by control means 106, order reversing circuit 302 couplesconductors 116 IB 116-nB to 116-1C 116- nC, respectively. However, inthe case where a' beam direction in the second quadrant is selected bycontrol means 106, order reversing circuit 302 couples conductors116lB'. 116-nB to conductors 116-nC 116-IC, respectively. Thus, orderreversing circuit 302 provides the same function as does the reversiblehorizontal phase counter 112 in the embodiment shown in FIGS. 1A and 1B,namely, providing a delay which increases from left to right or fromright to left, as the case may may be determined by choosing be, fordelay line audio frequency generators 120-l 120-n. Each order reversingcircuit merely consists of two sets of AND gates, either one of which isopened and the other one of which is closed under the control of controlmeans 106.

It will be seen that if delay lines 300-1 300-n are omitted, horizontalphase counter 112A plus order reversing circuit 302 may be substitutedfor reversible horizon- 10 tal phase counter 112 in FIGS. 1A and 13 evenwhen no virtual planar array is desired.

Even when the physical array is planar, under certain conditions, it maybe desirable to use fixed delays to produce a virtual planar array atsome fixed angle, such as 45, with respect to the physical planar array.This is because steering steps are relatively crude toward en-fire withrespect to steering steps closer to broadside of the array. Forinstance, with a 15 me. clock, it is possible to obtain steering stepsof approximately 0.2 when the angle of the planar array and thedirection of the beam is between 30 and 45; while if this angle is lessthan 10, the smallest steering steps obtainable is greater than 0.5. Byproviding a virtual array'at 45 with respect to the physical array, asubstantially end-fire beam makes an angle of close to 45 with respectto the virtual array, rather than the angle of. close to 0 which itmakes with respect to the physical array.

Although for illustrative purposes, only certain basic embodiments ofthe present invention have been shown. It is realized that it is withinthe skill of the art to add various subsidiary features, such asfrequency modulation of the audio square wave by varying the frequencyof the audio square wave under the control of control means 106,amplitude modulation of the audio wave by refinement of output levelstore 126 so that the output level is not only a function of beamdirection but is a function of an applied modulation frequency, any ofwhich may be desirable in a sophisticated sonar system. Therefore, it isintended that the present invention not be restricted to the specificembodiments disclosed, but that it be limited only by the true spiritand scope of the appended claims.

What is claimed is:

1. A phase control system for a two-d'mensional fixed transmitting arraycomposed of a plurality of individual transducers arranged in a firstnumber of rows and a second number of columns; said system comprising aclock pulse source for generating clock pulses at a predetermined pulserepetition period; control pulse generating means synchronized bysaid-clock pulses for generating first control pulses at a firstpreselected repetition period which is an integral multiple of saidpredetermined period and for generating second control pulses at asecond preselected repetition period which is an integral multiple ofsaid predetermined period; a group of delay line signal frequencygenerators equal in number to one of said fi'st and second numbers;first control pulse steering counter means coupled between said controlpulse generating means and said group of delay line signal frequencygenerators for sequentially applying successive fi' st control pulsesrespectively as an input to each separate one of said group of delayline signal frequency generators; each of said group of deiay linesignal frequency generators,

comprising a bistable device for producing a fist leve potential when inits first stable condition and a second level when in its second stablecondition and a recirculation loop, said loop comprising delay meansincluding a delay line, input means to which said first control pulse isapplied for applying an input pulse'to said delay means, output meansfor extracting an output pulse from said delay means in response to aninput pulse being applied thereto, and recirculation means coupling saidoutput means to said input means for applying an output pulse as aninput pulse to said delay means, said loop having a total loop delayequal to a given integral multiple of said predetermined period, saidpredetermined period multiplied by said given integral multiple beingequal to on:- half said signal frequency period, each of said group ofdelay line signal frequency generators further comprising mean couplingsaid output means of the loop thereofto the input of said bistabledevice thereof for switch ng said bistable device thereof from its firstto second stable condition in response to each odd output pulse appliedthereto and from its second to its first stable condition in response toeach even output pulse applied thereto,

whereby the bistable device of each of said groups of delay line signalfrequency generators produces a square wave output having a fundamentalfrequency equal to said signal frequency and a relative phase determined.by the time of application of a first control pulse to that delay linesignal frequency generator, and a low-pass filter coupled to saidbistable device thereof for passing only said fundamental frequency towhich said square wave output thereof is applied to convert said squarewave output thereof into a sinusoidal wave; a group of disabled timeslot means equal in number to the other of said first and secondnumbers, each of said time slot means when enabled producing at a givenfrequency at least twice said signal frequency repetitive time frameseach consisting of a plurality of distinctive time slots equal in numberto said one number; second control pulse steering counter means coupledbetween said control pulse generating means and said group of time slotmeans for sequentially applying successive second control pulsesrespectively as an input to each separate one of said group of time slotmeans to effect the enabling thereof in response thereto; an individualstore means corresponding to each of said delay line signal frequencygenerators; sampling means controlled by one of said time slot means fonsampling said sinusoidal wave of each of said delay line signalfrequency generator once during each successive time of that time slotmeans and applying each sample to the corresponding store means; anindividual line circuit including a low-pass filter for passng only saidsignal frequency coupled to each transducer; an individual group ofnormally closed gate means corresponding wIth each time slot means, eachgroup of gate means including a member thereof corresponding to eachdelay line signal frequency generator, whereby a single gate meansuniquely corresponds with each line circuit; means coupling the outputof each store means to the input of that member of each group of gatemeans corresponding therewith; means for coupling the output of eachgate means to the low-pass filter of the line circuit with which ituniquely corresponds; and means coupling each time slot means to thegroup of gate means corresponding thereto for sequentially opening eachmember thereof during the occurrence of a separate one of saiddistinctive time slots of successive time frames thereof, whereby eachline circuit applies a sinusoidal wave having said signal frequency anda phase determined by said first and second preselected repetitionperiods to the transducer to which it is coupled.

2. The system defined in claim 1, further comprising control means forselecting said first preselected repetition period of said first controlpulses and said second preselected repetition period of said secondcontrol pulses in accordance with the desired angular direction of abeam to betransmitted from said array.

3. The system defined in claim 2, including level determining meanscoupled to said control means for controlling the relative amplitudes ofthe respective sinusoidal waves applied to the respective transducer inaccordance with said desired angular direction.

4. The system defined in claim 3, wherein said level determining meansincludes a plurality of separate points of different fixed potential,time division multiplex means including an output level store controlledby said control means for coupling said line circuits respectively toselected ones of said separate points in accordance with said desiredangular direction, and power supply means within each line circuitresponsive to the value of the fixed potential of the selected pointcoupled to that line circuit for controlling the amplitude of thesinusoidal Wave emanating from that line circuit in accordancetherewith.

' 5. The system defined in claim 2, wherein said first control pulsesteering counter means is a reversible counter, and means coupling saidfirst control pulse steering counter means to said control means foreffecting counting in 12 a forward direction when said desired angulardirection lies in the first azimuth quadrant and for effecting countingin a reverse direction when said desired angular direction lies in thesecond azimuth quadrant.

6. The system defined in claim 2, wherein said second control pulsesteering counter means is a reversible counter, and means coupling saidsecond control pulse steering counter means to said control means foreffecting counting in a forward direction when said angular directionlies in the first elevation quadrant and for effecting counting in areverse direction when said desired angular direction lies in the fourthelevation quadrant.

7. The system defined in claim 1, wherein said array is a planar arraywith adjacent transducers in each row being equally spaced from eachother and with adjacent transducers in each column being equally spacedfrom each other.

8. The system defined in claim 1, wherein said array is linear in atleast one dimension, and including virtual plane producing means forproducing a virtual plane displaced from said array composed of anindividual point in said virtual plane corresponding to each transducerin said array wherein adjacent points in each row are equally spacedfrom each other and adjacent points in each column are equally spacedfrom each other, said virtual plane producing means comprising anindivdual delay line coupled to the input of each respective delay linesignal frequency generator through which the first control pulse appliedthereto is applied from said first control pulse steering counter means,each delay line corresponding with those transducers associated with thedelay line signal frequency generator to which it is equal to thedisplacement of the points in said virtual plane corresponding to thosetransducers from those transducers divided by the velocity ofpropagation of transmitted energy in the medium surrounding said array.

9. The system defined in claim 8, wherein said array is non-planar, andwherein each transducer of said array is positioned at the intersectionof said array with a line connecting the point of said virtual planecorresponding to that transducer with a common point on the other sideof said array from said virtual plane.

10. The system defined in claim 1, wherein said recirculation loop ofeach delay line signal frequency generator further includes a monostablemultivibrator in series with said delay line thereof, said monostablemultivibrator producing an output pulse in response to an input pulseapplied thereto after a time delay which is determined by the magnitudeof bias potential applied to that monostable multivibrator, and controlmeans coupled to the monostable multivibrator of each delay line signalfrequency generator to control the magnitude of said bias potential tothereby control the signal frequency of the generated sinusoidal wave.

11. The system defined in claim 1, further including an audio pulsetimer means coupled to said group of time slot means to render said timeslots effective for opening said gate means solely intermittenttransmittingtime periods, the initiation and length of said transmittingtime periods being controlled by said timer means.

12. A phase control system for a two-dimensional fixed transmittingarray composed of a plurality of individual transducers arranged in afirst number of rows and a second number of columns; said systemcomprising a clockpulse source for generating clock pulses at apredetermined pulse repetition period; control pulse generating meanssynchronized by said clock pulses for generating first control pulses ata first preselctedrepetition period which is an integral multiple ofsaid predetermined period and for generating second control pulses at asecond preselected repetition period which is an integral multiple ofsaid pretdetermined period; a group of delay line signal frequencygenerators equal in number to one of said first and second numbers;first control pulse steering counter means coupled between said controlpulse generating means and said group of delay line signal frequencygenerators for spectively as an input to each separate one of said groupof delay line signal frequency generators; each of said group of delayline signal frequency generators comprising a bistable device forproducing a first level potential when in its first stable condition anda second level potential when in its second stable condition and arecirculation loop, said loop comprising delay means including a delayline, input means to which said first control pulse is applied forapplying an input pulse to said delay means, output means for extractingan output pulse from said delay means in response to an input pulsebeing applied thereto, and recirculation means coupling said outputmeans to said input means for applying an'output pulse as an input pulseto said delay means, said loop having a total loop vdelay equal to agiven integralmultiple of said predetermined period, said predeterminedperod multipled by said given integral multiple being equal to one-halfsaid signal frequency period, each of said group of delay line signalfrequency generators further comprising means coupling said output meansof the loop thereof to the input of said bistable device thereof forswitching said bistable device thereof-from its first to second stablecondition in response to each odd output pulse applied thereto and fromits second to its first stable condition in response to each even outputpulse applied thereto whereby the bistable device of when enabledproducing at a given frequency at least twice said signal frequencyrepetitive time frames each consisting of a plurality of distinctivetime slots equal in number to said one number; second control pulsesteering counter means coupled between said control pulse generatingmeans and said group of time slot means for sequentially applyingsuccessive second-control pulses respectively as an input to eachseparate one of said group of time slot means to effect the enablingthereof in response thereto; an individual store means corresponding toeach of said delay line signal frequency generators; sampling meanscontrolled by one of said time slot means for sampling said sinusoidalwave of each of said delay line signal frequency generator once duringeach successive time of that time slot means and applying each sample tothe corresponding store means; an individual line circuit including aeach said group of delay line signal frequency generators produces asquare wave output having a fundamental frequency equal to said signalfrequencies and a relative phase determined by the time of applicationof. a first control pulse to that delay line signal frequency generator,a low pass filter coupled to said bistable device for passing only saidfunadmental frequency to convert said square wave output into asinusoidal wave and time division multiplex means for coupling saidsinusoidal wave to each of said transducers. I

13. The invention as set forth in claim 12 wherein said time divisionmultiplex means comprises a group of disabled time slot means equal innumber to the other of said first and second numbers, each of said timeslot means low-pass filter for passing only said signal frequencycoupled to each transducer; an individual group of normally closed gatemeans corresponding with each time slot means, each group of gate meansincluding a member thereof corresponding to each delay line signalfrequency generator, whereby a single gate means uniquely correspondswith each line circuit; means coupling the output of each store means tothe input of that member of each group of gate means correspondingtherewith; means for coupling the output of each gate means to thelow-pass filter of the line circuit with which it uniquely corresponds;and means coupling each time slot means to the group of gate meanscorresponding thereto for sequentially opening each member thereofduring the occurrence of a separate one of said distinctive time slotsof successive time frames thereof, whereby each line circuit applies asinusoidal wave having said signal frequency and a phase detremined bysaid first and second preselected repetition periods to the transducerto which it is coupled.

No references cited.

RODNEY D. BENNETT, Primary Examiner.

R. A. FARLEY, Assistant Examiner.

12. A PHASE CONTROL SYSTEM FOR A TWO-DIMENSIONAL FIXED TRANSMITTINGARRAY COMPOSED OF A PLURALITY OF INDIVIDUAL TRANSDUCERS ARRANGED IN AFIRST NUMBER OF ROWS AND A SECOND NUMBER OF COLUMNS; SAID SYSTEMCOMPRISING A CLOCK PULSE SOURCE FOR GENERATING CLOCK PULSES AT APREDETERMINED PULSE REPETITION PERIOD; CONTROL PULSE GENERATING MEANSSYNCHRONIZED BY SAID CLOCK PULSES FOR GENERATING FIRST CONTROL PULSES ATA FIRST PRESELECTED REPETITION PERIOD WHICH IS AN INTEGRAL MULTIPLE OFSAID PREDETERMINED PERIOD AND FOR GENERATING SECOND CONTROL PULSES AT ASECOND PRESELECTED REPETITION PERIOD WHICH IS AN INTEGRAL MULTIPLE OFSAID PREDETERMINED PERIOD; A GROUP OF DELAY LINE SIGNAL FREQUENCYGENERATORS EQUAL IN NUMBER TO ONE OF SAID FIRST AND SECOND NUMBERS;FIRST CONTROL PULSE STEERING COUNTER MEANS COUPLED BETWEEN SAID CONTROLPULSE GENERATING MEANS AND SAID GROUP OF DELAY LINE SIGNAL FREQUENCYGENERATORS FOR SEQUENTIALLY APPLYING SUCCESSIVE FIRST CONTROL PULSESRESPECTIVELY AS AN INPUT TO EACH SEPARATE ONE OF SAID GROUP OF DELAYLINE SIGNAL FREQUENCY GENERATORS; EACH OF SAID GROUP OF DELAY LINESIGNAL FREQUENCY GENERATORS COMPRISING A BISTABLE DEVICE FOR PRODUCING AFIRST LEVEL POTENTIAL WHEN IN ITS FIRST STABLE CONDITION AND A SECONDLEVEL POTENTIAL WHEN IN ITS SECOND STABLE CONDITION AND A RECIRCULATIONLOOP, SAID LOOP COMPRISING DELAY MEANS INCLUDING A DELAY LINE, INPUTMEANS TO WHICH SAID FIRST CONTROL PULSE IS APPLIED FOR APPLYING AN INPUTPULSE TO SAID DELAY MEANS, OUTPUT MEANS FOR EXTRACTING AN OUTPUT PULSEFROM SAID DELAY MEANS IN RESPONSE TO AN INPUT PULSE BEING APPLIEDTHERETO, AND RECIRCULATION MEANS COUPLING SAID OUTPUT MEANS TO SAIDINPUT MEANS FOR APPLYING AN OUTPUT PULSE AS AN INPUT PULSE TO SAID DELAYMEANS, SAID LOOP HAVING A TOTAL LOOP DELAY EQUAL TO A GIVEN INTEGRALMULTIPLE OF SAID PREDETERMINED PERIOD, SAID PREDETERMINED PERIODMULTIPLED BY SAID GIVEN INTEGRAL MULTIPLE BEING EQUAL TO ONE-HALF SAIDSIGNAL FREQUENCY PERIOD, EACH OF SAID GROUP OF DELAY LINE SIGNALFREQUENCY GENERATORS FURTHER COMPRISING MEANS COUPLING SAID OUTPUT MEANSOF THE LOOP THEREOF TO THE INPUT OF SAID BISTABLE DEVICE THEREOF FORSWITCHING SAID BISTABLE DEVICE THEREOF FROM ITS FIRST TO SECOND STABLECONDITION IN RESPONSE TO EACH ODD OUTPUT PULSE APPLIED THERETO AND FROMITS SECOND TO ITS FIRST STABLE CONDITION IN RESPONSE TO EACH EVEN OUTPUTPULSE APPLIED THERETO WHEREBY THE BISTABLE DEVICE OF EACH SAID GROUP OFDELAY LINE SIGNAL FREQUENCY GENERATORS PRODUCES A SQUARE WAVE OUTPUTHAVING A FUNDAMENTAL FREQUENCY EQUAL TO SAID SIGNAL FREQUENCIES AND ARELATIVE PHASE DETERMINED BY THE TIME OF APPLICATION OF A FIRST CONTROLPULSE TO THAT DELAY LINE SIGNAL FREQUENCY GENERATOR, A LOW PASS FILTERCOUPLED TO SAID BISTABLE DEVICE FOR PASSING ONLY SAID FUNDAMENTALFREQUENCY TO CONVERT SAID SQUARE WAVE OUTPUT INTO A SINUSOIDAL WAVE ANDTIME DIVISION MULTIPLEX MEANS FOR COUPLING SAID SINUSOIDAL WAVE TO EACHOF SAID TRANSDUCERS.